One of the most important rules of etiquette is to never sell something that was given to you as a gift. I don’t care how much you hate it or will never use it: you either regift it to someone, throw it away, or let it sit in your basement for the rest of time. Some people might think that throwing it away and selling it are morally comparable, but it’s wrong to profit off a gift your family member or friend gave you out of their heart’s kindness. Not everybody agrees with me on this, and I think there are blurred lines. If your older cousin gave you her hand-me-downs, and you sell a couple of the shirts that don’t fit you on Depop, I’m not sure if that’s crossing a line. There’s a difference between giving something precious and getting rid of your old stuff that you’ll never use again.